JP3220896B2 - Injection locked oscillator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a microwave and millimeter wave injection locked oscillator.

[0002]

2. Description of the Related Art FIG. 8 shows an example of an injection locked oscillator using a conventional circulator. In an oscillator having a configuration in which an oscillation circuit 104 is connected to one terminal 102 of the circulator 100 and an oscillation output is taken out from a circulator terminal 103, an external forcing signal is input to a first circulator terminal 101 to perform injection synchronization. The arrow indicates the signal transmission direction of the circulator, and the direction (irreversibility) separates the terminals. Oscillation circuits include a structure in which a negative resistance diode is disposed at a certain distance from the waveguide short-circuit surface to cause resonance, and a structure in which a strip conductor is used for resonance.

FIG. 9 shows an example of an injection-locked oscillator in which a directional coupler and an amplifier are combined. A signal is injected from a terminal 111 of a directional coupler 110 and an amplifier is provided between a passing terminal 112 and an isolation terminal 113. 115 are connected. Here, the terminals 113 and 112 of the directional coupler
Is a coupling terminal as viewed from the amplifier, and forms a feedback circuit between the input and output of the amplifier 115;
Oscillation occurs when the phase around the 12 loops is an integral multiple of 2π and has a gain of 1 or more. When an injection signal is input to this oscillator via the terminal 111, the oscillation frequency is synchronized with the injection signal, and the oscillation output is taken out from the terminal 114.

However, the injection-locked oscillator shown in FIGS. 8 and 9 uses a non-reciprocal circulator or directional coupler to separate the injection signal and the oscillation signal. There was an operating frequency band limitation due to the four wavelength line. The band is about 10% to 50% of the center frequency. Therefore, the subharmonic frequency (1 / n of the oscillation frequency f ₀ : n = 2,
3, 4...) Could not be synchronized. Further, since a ferrite element is used, it is difficult to make an IC. Further, since the oscillator loop and the injection signal terminal or the oscillation output terminal are not electrically separated, there is an influence of an external circuit connected to the injection locked oscillator. On the other hand, in the conventional example in which the subharmonic injection locking is performed, the injection signal path and the oscillation frequency path have to be electrically separated by a circuit configuration having a filter function, so that the subharmonic coefficient 1 / n is limited. At the same time, the fundamental wave (n
= 1) could not be synchronized.

FIG. 10 shows an injection-locked oscillator (IEEE Int) using a nonreciprocal four-terminal circuit to solve the above problems.
international Microwave Symp
Osium Digest 1994, pp. 13-1
6). Terminal 121 or the signal input from terminal 121 is distributed only to terminals 123 and 124,
In the non-reciprocal four-terminal circuit 120 in which no signal is transmitted between 21-123 and between terminals 122-124, the terminal 12
An amplifier 125 is connected between the terminal 3 and the terminal 122. Here, the terminal 122 and the terminal 123 are coupling terminals as viewed from the amplifier 125, and form a feedback circuit between the input and output of the amplifier 125. The phase rotation of the loop of 122-125-123-122 is an integral multiple of 2π. Oscillation occurs when having more than one gain. When an injection signal is input to this oscillator via the terminal 121, the oscillation frequency is synchronized with the injection signal, and the oscillation output is taken out from the terminal 124. The nonreciprocal four-terminal circuit 120 formed of transistors here has a fundamental wave of n = 1 and n = 2,
Since the operation of the four-terminal circuit is maintained for the sub-harmonics of 3, 4,..., The value of the sub-harmonic coefficient 1 / n can be set freely, and the sub-harmonic with a small sub-harmonic coefficient 1 / n can be set. Even when injection is performed, injection-locked oscillation occurs.

[0006]

Generally, the frequency pull-in range Δf of the injection locked oscillator is given by the following equation.

(Equation 1)

Where f ₀ is the free oscillation frequency of the oscillator,
Q _eff external Q, P ₀ of the oscillator output of the oscillator, P _i is the injected signal power from the outside. From the above equation, the smaller the Q _eff, or, frequency pull-in range is wider Higher P _i. However, it is difficult to realize a wide frequency pull-in range with a small input.

Also, in the circuit shown in FIG. 10 capable of sub-harmonic injection locking, the frequency pull-in range Δf1 when the n = 1 fundamental wave is injected and the frequency pull-in range Δf _n when the sub-harmonic is injected are as follows. There is an empirical relationship like a ceremony.

(Equation 2)

Here, 1 / n is a subharmonic coefficient. From the above equation, as the subharmonic coefficient 1 / n increases, the frequency pull-in range decreases. For example, n =
The frequency pull-in range is 500M when one fundamental wave is injected
In the case of Hz, the pull-in range of the sub-harmonic with n = 4 becomes 82 MHz, and the pull-in range of the sub-harmonic with n = 8 becomes 33 MHz, which is not practical. Further, even when the injection-locked oscillator is operated as a multiplier, a very narrow band circuit results.

The present invention improves the above-mentioned drawbacks of the prior art, and provides an injection-locked oscillator which enables a wide frequency pull-in range even when an injection signal having a small sub-harmonic coefficient n is input. It is in.

[0011]

SUMMARY OF THE INVENTION In order to achieve the above object, a feature of the present invention is to have first, second, and third terminals, and a first terminal, a second terminal, and a second terminal. A circulator whose signal transmission from the first terminal to the third terminal is irreversible, and an oscillator composed of an oscillating element operating in at least a part of an operating frequency band of the circulator and a variable phase shifter is connected to the second terminal. , An injection locked oscillator that receives an injection signal from the first terminal and obtains an oscillation output from the third terminal.

Further, another feature of the present invention is that the first, second,
A directional coupler having third and fourth terminals, wherein the directional coupler is electrically isolated between the first terminal and the third terminal and between the second terminal and the fourth terminal; Terminal and the third
An amplifier and a variable phase shifter that operate in at least a part of the operating frequency band of the directional coupler between the terminals,
An injection locked oscillator is provided in which an injection signal is input to the first terminal and an oscillation output is obtained from the fourth terminal.

Another feature of the present invention is that it has first, second, third, and fourth terminals, and between the first terminal and the third terminal and between the second terminal and the fourth terminal. An electrically isolated directional coupler, a 90-degree splitter operating between the second terminal and the third terminal in at least a part of an operating frequency band of the directional coupler; An injection locked oscillator includes an amplifier and an in-phase synthesis circuit, inputs an injection signal to the first terminal, and obtains an oscillation output from the fourth terminal.

Another feature of the present invention is that it has first and second input terminals and first and second output terminals,
The signal transmission from the input terminal to the first output terminal and the second output terminal is irreversible, and the signal transmission from the second input terminal to the first output terminal and the second output terminal is irreversible. A nonreciprocal four-terminal circuit in which a first input terminal and a second input terminal are electrically isolated from each other and a first output terminal and a second output terminal are electrically isolated; An amplifier operating between at least a part of the operating frequency band of the four-terminal circuit and a variable phase shifter between the second input terminals, inputting an injection signal to the first input terminal;
The injection oscillator obtains an oscillation output from the output terminal of the injection oscillator.

Another feature of the present invention is that it has first and second input terminals and first and second output terminals,
The signal transmission from the input terminal to the first output terminal and the second output terminal is irreversible, and the signal transmission from the second input terminal to the first output terminal and the second output terminal is irreversible. A nonreciprocal four-terminal circuit in which a first input terminal and a second input terminal are electrically isolated from each other and a first output terminal and a second output terminal are electrically isolated; A 90-degree distributor operating in at least a part of the operating frequency band of the four-terminal circuit between second input terminals, a variable amplifier and an in-phase synthesis circuit, and an injection signal is input to the first input terminal And an injection locked oscillator for obtaining an oscillation output from the second output terminal.

Another feature of the present invention is that the irreversible
A terminal circuit having four common-gate FETs, a source of the first common-gate FET and a source of the second common-gate FET connected to the first input terminal, and a source of the third common-gate FET; And a source of the fourth common-gate FET is connected to the second input terminal, a drain of the first common-gate FET and a drain of the third common-gate FET are connected to the first output terminal, In the injection locked oscillator, the drain of the second common-gate FET and the drain of the fourth common-gate FET are connected to the second output terminal.

With the above-described configuration, by changing the phase amount of the variable phase shifter, the phase rotation of the oscillator changes, and the free oscillation frequency can be changed. Therefore,
Assuming that the amount of change in the free oscillation frequency is Δf ₀ , the frequency pull-in range Δf of the injection locked oscillator can be expressed by the following equation.

(Equation 3)

As a result, the frequency pull-in range is widened by the same amount as the free oscillation frequency as compared with the conventional injection-locked oscillator regardless of the level of the injection signal, and a wide pull-in range is realized for a small input signal input. be able to. The same applies to the conventional example shown in FIG. 9 in which sub-harmonic injection is also possible. When the sub-harmonic with the sub-harmonic coefficient 1 / n represented by the above equation (2) is injected, the frequency pull-in range Δf _n is ,

(Equation 4) Becomes That is, an arbitrary subharmonic coefficient 1 / n
, A wide frequency pull-in range can be realized, and the device can also operate as a broadband frequency multiplier.

Further, the circuit including the 90-degree distributor, the variable amplifier and the in-phase synthesizing circuit operates as a phase shifter for vector synthesis with a gain, so that the free oscillation frequency can be changed. First, the operation principle will be described with reference to FIG. FIG. 7 shows the electrical amplitude and phase relationship of a signal at a certain frequency in a polar coordinate system. The magnitude from the center point indicates the amplitude, and the rotation angle θ of the circle indicates the phase (one rotation). Is 360 degrees). When a signal of one frequency at the operating frequency of the 90-degree divider, the variable amplifier, and the in-phase combining circuit is injected into the loop, first, the signal is distributed as two signals having a 90-degree phase difference by the 90-degree distributor, and each of the signals is varied. Input to the amplifier. The two signals amplified by the variable amplifier are vector-combined again by the in-phase combining circuit, re-input to the loop as one signal having an electric phase θ, and freely oscillate if the gain of the loop is 1 or more. Therefore, by adjusting the gains of the two variable amplifiers, the signal output from the combining circuit can be changed on the concentric circle from point A to point B in FIG. 7, so that the oscillation frequency can be largely changed. That is, the oscillation frequency at point B is set to f _{OS
If C} , the oscillation frequency at point A is 4 / 3f _OSC , so that the oscillation frequency can be changed with a maximum bandwidth of 33%. _Assuming that the phase rotation in the loop is 360 degrees in the vector component of point B in the signal of f _OSC , the other vector component is 270 degrees delayed by 90 degrees. frequencies of the phase rotation is obtained _{4 / 3f OSC (= f OSC} × 360/2
70). When the insertion loss of the 90-degree distributor and the in-phase combining circuit is zero, the gain required for the variable amplifier does not increase.

[0020]

Embodiments of the present invention will be described below with reference to the drawings.

(First Embodiment) FIG. 1 shows a first embodiment of the injection locked oscillator of the present invention.

In FIG. 1, 10 is a three-terminal circulator, 11 is a first terminal, 12 is a second terminal, 13
Is a third terminal. The signal input from the terminal 11 is transmitted only to the terminal 12, the signal input from the terminal 12 is transmitted only to the terminal 13,
No signal is transmitted from the terminal to the terminal 11 and the terminal 12. The arrows in FIG. 1 indicate the signal transmission. Reference numeral 16 denotes a variable phase shifter, and 17 denotes an open-ended or short-circuited resonator including the variable phase shifter 16. The resonator 17 is connected to the oscillation element 15 via the terminal 14. When the oscillation element 15 is viewed from the terminal 14, the oscillation element 15 appears as a negative resistance element. The terminal 18 including the oscillation element 15 and the resonator 17 is connected to the terminal 1.
4 operates as an oscillator whose free oscillation frequency is determined by a signal reflected from the resonator 17. When an injection signal is input from the terminal 11 of the circulator 10, the oscillator 18
Oscillates synchronously with the injection signal, and an output can be obtained via the terminal 13. Further, since the phase amount of the signal returning to the terminal 14 changes according to the phase amount of the variable phase shifter 16, the free oscillation frequency can be changed. Therefore, the injection-locked oscillator shown in FIG. 1 can realize a wide pull-in range even for a small injection signal input. In the embodiment, the three-terminal circulator is used. However, the present invention is not limited to this, and a four-terminal or more multi-terminal circulator may be used.

(Second Embodiment) FIG. 2 shows a second embodiment of the injection locked oscillator of the present invention.

In FIG. 2, reference numeral 20 denotes a directional coupler.
21 is a first terminal, 22 is a second terminal, 23 is a third terminal, and 24 is a fourth terminal. In the directional coupler 20, the signal input from the terminal 21 or the terminal 23 is transmitted to the terminals 22 and 24, and the terminal 21 and the terminal 23 are electrically isolated. 60 is an amplifier, 61
And 62 are an input terminal and an output terminal, respectively. 70 is a variable phase shifter (or a cascade connection between the variable phase shifter and the delay line), and 71 and 72 are an input terminal and an output terminal, respectively. The input terminal 61 of the amplifier 60 is connected to the terminal 22 of the directional coupler 20, the output terminal 62 of the amplifier 60 is connected to the input terminal 71 of the variable phase shifter 70, and the output terminal 72 of the variable phase shifter 70 is It is connected to the terminal 23 of the sex coupler 20. Here, the terminals 23 and 2 of the directional coupler 20 are connected.
Reference numeral 2 denotes a coupling terminal as viewed from the amplifier 60, and forms a feedback circuit between the input and output of the amplifier 60 to form a feedback circuit 22-61-62-71.
Free oscillation occurs when the phase around the -72-23-22 loop is an integral multiple of 2π and has a gain of 1 or more. When an injection signal is input to this oscillator via the terminal 21, the oscillation frequency is synchronized with the injection signal, and the oscillation output is taken out from the terminal 24. Further, since the free oscillation frequency can be changed depending on the phase amount of the variable phase shifter 70, a wide pull-in range can be realized even for a small input signal input.

(Third Embodiment) FIG. 3 shows a third embodiment of the injection locked oscillator of the present invention.

In FIG. 3, reference numeral 20 denotes a directional coupler.
21 is a first terminal, 22 is a second terminal, 23 is a third terminal, and 24 is a fourth terminal. In the directional coupler 20, the signal input from the terminal 21 or the terminal 23 is transmitted to the terminals 22 and 24, and the terminal 21 and the terminal 23 are electrically isolated. Reference numeral 80 denotes a 90-degree distributor, 80a denotes an input terminal of the 90-degree distributor 80, 80b and 80c denote output terminals, and the terminals 80b and 80c are electrically isolated. 90 and 91 are variable amplifiers, 90a and 91a are input terminals, and 90b and 91b are output terminals. Further, reference numeral 85 denotes an in-phase synthesizing circuit, 85a and 85b denote input terminals of the in-phase synthesizing circuit 85, 80c denotes an output terminal, and the terminals 85a and 85b are electrically isolated. The input terminal 80a of the 90-degree distributor 80 is connected to the terminal 22 of the directional coupler 20, and the output terminal 80b (80c) of the 90-degree distributor 80 is connected to the input terminal 90a (91a) of the variable amplifier 90 (91). The output terminal 90b (9) of the variable amplifier 90 (91)
1b) is an input terminal 85a (85b) of the in-phase synthesis circuit 85
The output terminal 85 c of the in-phase combining circuit 85 is connected to the terminal 23 of the directional coupler 20. Here, the terminals 23 and 22 of the directional coupler 20 are connected to the variable amplifier 90.
It is a coupling terminal viewed from (91), and is an amplifier 90 (91)
A feedback circuit is formed between the input and output of 22-80-90 (9
1) Free oscillation occurs when the phase around the -85-23-22 loop is an integral multiple of 2π and has a gain of 1 or more. When an injection signal is input to this oscillator via a terminal 21,
The oscillation frequency is synchronized with the injection signal, and the oscillation output is taken out from the terminal 24.

In the third embodiment, the 90-degree distributor 8
0, a circuit composed of the variable amplifier 90 (91) and the in-phase synthesizing circuit 85 operates as a phase shifter for vector synthesis with a gain, and can change the free oscillation frequency in a band of up to 33%. A wide pull-in range can be realized even for signals. The method of changing the oscillation frequency using the vector synthesis by the 90-degree distributor, the variable amplifier, and the in-phase synthesis circuit realizes an injection-locked oscillator having a wider frequency variable than the method of inserting a variable phase shifter in a loop. Suitable for you. That is, when the phase amount is 3
An infinite phase shifter that can be changed by 60 degrees now has an insertion loss of 10 dB
As described above (for example, the Institute of Electronics, Information and Communication Engineers, Autumn Meeting C-71, 1994), one additional operation is required to obtain the free oscillation operation.
Since an amplifier requires a gain of 0 dB or more, it is difficult to realize an injection locked oscillator. Further, in the phase shifter using the variable capacitance of the active device by the bias control, the insertion loss increases in proportion to the variable width, so that only a band of about 10% can be actually obtained. On the other hand, a hybrid that is a 90-degree divider and a Wilkinson divider that is an in-phase divider include those having about 1 dB even in the 20 GHz band (for example, IEEE Tran).
s. Microwave Theory and Te
chniques, vol. 43, no. 6, pp. 1
270-1275, June 1995), no excessive gain for the amplifier is required.

(Fourth Embodiment) FIG. 4 shows a fourth embodiment of the injection locked oscillator of the present invention. 4, the same components as those in FIG. 2 are denoted by the same reference numerals.

Reference numeral 30 denotes a nonreciprocal four-terminal circuit, 31 is a first input terminal, 33 is a second input terminal, 32 is a first output terminal, and 34 is a second output terminal. The signal input from terminal 31 is distributed only to terminals 32 and 34, the signal input from terminal 33 is distributed only to terminals 32 and 34, and no signal is transmitted between terminals 31-33 and between terminals 32-34. (Isolated). Arrows in the figure show the state of the signal transmission. 60 is an amplifier, 61
And 62 are an input terminal and an output terminal, respectively. 70 is a variable phase shifter (or a cascade connection between the variable phase shifter and the delay line), and 71 and 72 are an input terminal and an output terminal, respectively. The input terminal 61 of the amplifier 60 is connected to the terminal 32 of the four-terminal circuit 30, the output terminal 62 of the amplifier 60 is connected to the input terminal 71 of the variable phase shifter 70, and the output terminal 72 of the variable phase shifter 70 has four terminals. It is connected to the terminal 33 of the circuit 30. Here, the terminal 33 and the terminal 32 of the four-terminal circuit 30 are coupling terminals as viewed from the amplifier 60, and form a feedback circuit between the input and output of the amplifier 60, thereby forming a 32-61-62-71-72.
Free oscillation occurs when the phase around the loop -33-32 is an integral multiple of 2π and has a gain of 1 or more.

When a signal of high stability and low phase noise is input from the terminal 31 of the four-terminal circuit 30, a part of the signal is input to the amplifier 60 via the terminal 32, and a harmonic is generated due to the nonlinearity of the oscillating amplifier. When the harmonic is near the above-mentioned free oscillation frequency, the oscillation frequency and the harmonic wave undulate, and the state changes so that this becomes zero, and the oscillation state is synchronized with the injection signal. The oscillation output is output to the terminal 34 via the terminal 33, and does not appear at the signal input terminal 31 due to the irreversibility of the four-terminal circuit 30. Therefore, even if the terminal 31 is in a mismatched state, part of the oscillation output
And is not re-injected into the oscillation loop.
Similarly, the reflected wave at terminal 34 does not appear at any of the other terminals and is not re-injected. That is, the configuration is hardly affected by the external circuit.

Also, by changing the phase amount of the variable phase shifter to change the free oscillation frequency, the change amount of the free oscillation frequency Δf
_The range of synchronization increases according to ₀ . That is, the frequency pull-in range Δf _n when a subharmonic with a subharmonic coefficient 1 / n of 以下 or less is injected is

(Equation 5) Becomes If the free oscillation frequency change amount Δf ₀ is sufficiently obtained,
A wide frequency pull-in range can be realized at an arbitrary subharmonic coefficient 1 / n.

(Fifth Embodiment) FIG. 5 shows a fifth embodiment of the injection locked oscillator of the present invention. 5, the same components as those in FIG. 3 are denoted by the same reference numerals.

Reference numeral 30 denotes a non-reciprocal four-terminal circuit, 31 is a first input terminal, 33 is a second input terminal, 32 is a first output terminal, and 34 is a second output terminal. The signal input from terminal 31 is distributed only to terminals 32 and 34, the signal input from terminal 33 is distributed only to terminals 32 and 34, and no signal is transmitted between terminals 31-33 and between terminals 32-34. (Isolated). Arrows in the figure show the state of the signal transmission. Reference numeral 80 denotes a 90-degree distributor; 80a, an input terminal of the 90-degree distributor 80;
0b and 80c are output terminals, and terminals 80b and 80c
c is electrically isolated. Also, 90, 9
1 is a variable amplifier, 90a and 91a are input terminals, 9
0b and 91b are output terminals. Further, 85 is an in-phase synthesis circuit, and 85a and 85b are in-phase synthesis circuits 85.
Are input terminals, and 85c is an output terminal.
5b is electrically isolated. The input terminal 80a of the 90-degree distributor 80 is connected to the terminal 32 of the four-terminal circuit 30, and the output terminal 80b (80c) of the 90-degree distributor 80.
Is the input terminal 90a (91a) of the variable amplifier 90 (91)
And an output terminal 90b of the variable amplifier 90 (91).
(91b) is an input terminal 85a (85
b), and the output terminal 85 c of the in-phase combining circuit 85 is connected to the terminal 33 of the four-terminal circuit 30. here,
The terminals 33 and 32 of the four-terminal circuit 30 are connected to a variable amplifier 90
It is a coupling terminal viewed from (91), and is an amplifier 90 (91)
A feedback circuit is formed between the input and output of
1) Free oscillation occurs when the phase around the -85-33-32 loop is an integral multiple of 2π and has a gain of 1 or more. When an injection signal is input to this oscillator via the terminal 31,
The oscillation frequency is synchronized with the injection signal, and the oscillation output is taken out from the terminal 34.

According to the fifth embodiment described above, in addition to the same effects as the third embodiment of the present invention, frequency synchronization can be performed even in a sub-harmonic having a large sub-harmonic coefficient n in a band of up to 33%. The range can be expanded.

(Sixth Embodiment) FIG. 6 shows a sixth embodiment of the injection locked oscillator of the present invention.

In FIG. 6, 41, 42, 51 and 5
Reference numeral 2 denotes a common-gate FET, and reference numerals 40 and 50 denote common-mode distribution circuits in which two common-gate FETs are combined as shown in FIG. 6, the same components as those in FIG. 4 are denoted by the same reference numerals. Here, since a field effect transistor is used as the transistor, S represents a source, D represents a drain, and G represents a gate.

In the four-terminal circuit 30, the signals output to the terminals 44 (54) and 45 (55)
(32), transmitted to terminal 32 (34), and transferred to terminal 34 (3
2) to terminals 31 (33), 32 (34), 33 (3
Transmission to 1) is blocked by the irreversibility of the distribution circuit. Further, since the output terminal impedance of each distribution circuit is very high, the signals distributed by the distribution circuit are transmitted to the terminals 32 and 34 as they are. Therefore, 4 in FIG.
A signal path set in the terminal circuit 30 is established at an arbitrary frequency (in a wide band). By combining the irreversible four-terminal circuit 30, the amplifier 60 and the variable phase shifter 70 as shown in FIG. 6, the fundamental wave of n = 1 and n = 2, 3, 4,.
・ Injection-locked oscillator synchronized with the sub-harmonic can be realized. Further, by changing the amount of phase by a variable phase shifter, a loop 32-61-62-71-72-33 is formed.
The frequency of free oscillation can be changed at -32. Since the change in the free oscillation frequency leads to a wider frequency pull-in range for all the injection signals, it has a wide frequency synchronization range even for a sub-harmonic having a large sub-harmonic coefficient n, which is difficult with a conventional injection-locked oscillator. An injection locked oscillator can be realized.

(Other Embodiments) In the fourth to sixth embodiments, a bipolar transistor may be used instead of a field effect transistor. In the embodiment, the common-gate FET is used. However, the present invention is not limited to this, and another common-type (common-drain or common-source) may be used. Since the distribution circuits 40 and 50 have a gain in the case of the common source, the gain of the amplifier 60 does not necessarily need to be 1 or more.

In the third and fifth embodiments,
A 90-degree divider, a variable amplifier, and an in-phase combining circuit are sequentially inserted in the oscillation loop. However, even the in-phase distributor, the variable amplifier, and the 90-degree combining circuit operate as a phase shifter for vector combining with gain. A similar effect is obtained.

[0040]

As described above, according to the present invention, 3
One terminal of a circulator having two terminals is connected to an oscillating element and a variable phase shifter that operate in a part of the operating frequency band of the circulator, and the other terminal is an input signal input terminal, and the other terminal is Because it is an oscillation output terminal,
A directional coupler, an amplifier operating in a part of an operating frequency band of the directional coupler, and a variable phase shifter, and one terminal of the directional coupler is used as an input terminal of an injection signal. And the amplifier and the variable phase shifter are connected between the passing terminal and the isolation terminal of the terminal, and the other passing terminal is used as an oscillation output terminal, so that two input terminals and two output terminals A non-reciprocal four-terminal circuit in which signal transmission between the input terminal and the two output terminals is irreversible, and the input signal terminal and the output terminal are electrically isolated. An amplifier operating in a part of the operating frequency band of the four-terminal circuit, and a variable phase shifter, wherein the amplifier and the variable phase shifter are connected between one output terminal and one input terminal of the four-terminal circuit. Connect a phase shifter, connect the other input terminal to the injection signal input terminal and the other output It is possible to configure the injection-locked oscillator since the child an oscillation output terminal.

In the injection-locked oscillator according to the present invention, the free oscillation frequency can be changed by the variable phase shifter, so that a wider frequency pull-in range can be realized even in the case of a small input signal level input. Further, a wide pull-in range can be realized even for a subharmonic injection signal having a large subharmonic coefficient.

Further, since the nonreciprocal four-terminal circuit can be constituted mainly by transistors, it can be realized as an IC and very small. In addition, since the portion that performs free oscillation, the injection signal input terminal, and the oscillation signal output terminal can be separated from each other due to the irreversibility of the transistor, it is possible to reduce the influence of a circuit or load connected to the outside. In addition, the sub-harmonic coefficient n can be freely selected because synchronization with an injection signal in a very wide frequency range can be achieved by the wide band characteristics of the transistor. Therefore, in combination with a commercially available synthesizer or the like, a very simple and economical microwave and millimeter wave band local oscillator / synthesizer can be configured without using a multiplier.

Also, by inserting a 90-degree distributor, a variable amplifier, and an in-phase synthesis circuit operating as a phase shifter for vector synthesis with a gain in the loop, the free oscillation frequency can be changed in a maximum 33% band. Therefore, even if the injection signal is at a low level or is a higher-order subharmonic, a wider pull-in range can be realized as compared with the related art. Since the method of changing the oscillation frequency by the vector synthesis does not require an excessive gain for the amplifier, an injection locked oscillator having a wide frequency pull-in range can be easily realized.

[Brief description of the drawings]

FIG. 1 is a circuit diagram of an injection locked oscillator according to a first embodiment of the present invention.

FIG. 2 is a circuit diagram of an injection locked oscillator according to a second embodiment of the present invention.

FIG. 3 is a circuit diagram of an injection locked oscillator according to a third embodiment of the present invention.

FIG. 4 is a circuit diagram of an injection locked oscillator according to a fourth embodiment of the present invention.

FIG. 5 is a circuit diagram of an injection locked oscillator according to a fifth embodiment of the present invention.

FIG. 6 is a circuit diagram of an injection locked oscillator according to a sixth embodiment of the present invention.

FIG. 7 is an operation principle diagram of a vector combining phase shifter including a 90-degree distributor, a variable amplifier, and an in-phase combining circuit.

FIG. 8 is a circuit diagram of a conventional injection locked oscillator using a circulator.

FIG. 9 is a circuit diagram of a conventional injection-locked oscillator using a directional coupler.

FIG. 10 is a circuit diagram of a conventional injection-locked oscillator using a non-reciprocal four-terminal circuit.

[Explanation of symbols]

 10 Three-terminal circulator 11, 12, 13, 14 terminal 15 Oscillator 16 Variable phase shifter 17 Resonator 18 Oscillator 20 Directional coupler 21, 22, 23, 24 terminal 30 Non-reciprocal four-terminal circuit 31, 32, 33, 34 terminal 40, 50 Common gate FET distribution circuit 41, 42, 51, 52 Common gate FET 43, 44, 45, 53, 54, 55 Terminal 60 Amplifier 70 Variable phase shifter 61, 62, 71, 72 Terminal 80 90 degrees Distribution circuit 80a, 80b, 80c Terminal 85 Directional coupler 85a, 85b, 85c Terminal 90, 91 Variable amplifier 90a, 90b, 91a, 91b Terminal 100 Circulator 101, 102, 103 Terminal 104 Oscillation circuit 110 Directional coupler 111, 112, 113, 114 terminal 115 amplifier 120 non-reciprocal 4 terminal times 121-124 terminal 125 amplifier S source D drain G gates

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H03L 7/24 H03F 1/00-7/06

Claims (6)

(57) [Claims] A circulator having first, second, and third terminals, wherein signal transmission from the first terminal to the second terminal and from the second terminal to the third terminal is irreversible; Second
Is connected to an oscillator composed of an oscillating element operating in at least a part of the operating frequency band of the circulator and an open-ended or short-circuited resonator including a variable phase shifter, and an injection signal from the first terminal. And an oscillation output is obtained from a third terminal. 2. A semiconductor device comprising: a first terminal; a second terminal; a third terminal; and a fourth terminal.
A directional coupler in which the terminals of the directional coupler are electrically isolated, and an amplifier that operates between the second terminal and the third terminal in at least a part of an operating frequency band of the directional coupler. An injection-locked oscillator having a variable phase shifter, wherein an injection signal is input to the first terminal and an oscillation output is obtained from the fourth terminal. 3. A semiconductor device comprising: a first terminal; a second terminal; a third terminal; and a fourth terminal.
And a directional coupler electrically isolated between the terminals of the directional coupler, and a 90-degree coupler operating between at least a part of an operating frequency band of the directional coupler between the second terminal and the third terminal. A splitter, two variable amplifiers connected to respective outputs of the splitter, and an in-phase synthesis circuit connected to the output of the variable amplifier; inputting an injection signal to the first terminal;
An injection locked oscillator, wherein an oscillation output is obtained from the fourth terminal. 4. A semiconductor device having first and second input terminals and first and second output terminals, wherein signal transmission from the first input terminal to the first output terminal and the second output terminal is irreversible. And the signal transmission from the second input terminal to the first output terminal and the second output terminal is irreversible, and between the first input terminal and the second input terminal and between the first output terminal and the first output terminal. A nonreciprocal four-terminal circuit in which the two output terminals are electrically isolated, and at least a part of the operating frequency band of the four-terminal circuit between the first output terminal and the second input terminal. An injection locked oscillator comprising an operating amplifier and a variable phase shifter, wherein an injection signal is input to the first input terminal and an oscillation output is obtained from the second output terminal. 5. A semiconductor device having first and second input terminals and first and second output terminals, wherein signal transmission from the first input terminal to the first output terminal and the second output terminal is irreversible. And the signal transmission from the second input terminal to the first output terminal and the second output terminal is irreversible, and between the first input terminal and the second input terminal and between the first output terminal and the first output terminal. A nonreciprocal four-terminal circuit in which the two output terminals are electrically isolated, and at least a part of the operating frequency band of the four-terminal circuit between the first output terminal and the second input terminal. A 90-degree divider that operates, a variable amplifier connected to each output of the divider, and an in-phase synthesis circuit connected to the output of the variable amplifier. An injection signal is input to the first input terminal. Wherein an oscillation output is obtained from the second output terminal. 6. The non-reciprocal four-terminal circuit has four common-gate FETs, and connects a source of a first common-gate FET and a source of a second common-gate FET to the first input terminal. Connecting the source of the third common-gate FET and the source of the fourth common-gate FET to the second input terminal, and connecting the drain of the first common-gate FET and the drain of the third common-gate FET to the second input terminal. 6. The injection locking device according to claim 4, wherein the first output terminal is connected to the first output terminal, and the drain of the second common-gate FET and the drain of the fourth common-gate FET are connected to the second output terminal. Oscillator.